As with all of our Web API methods, dialog.open primarily takes URL-encoded parameters as arguments. Similar to chat.postMessage, chat.unfurl, and chat.update this method also includes a parameter that expects a JSON object encoded with application/x-www-form-urlencoded.

Response

Assuming your submitted dialog elements were properly formatted, valid, and the trigger_id was viable, you will receive a minimal success response.

Typical success response is quite minimal.

{
"ok": true
}

Typical error response, before getting to any possible validation errors.

{
"ok": false,
"error": "missing_trigger"
}

The impossibility of all possible errors expressed in a single response:

{
"ok": false,
"error": "validation_errors",
"response_metadata": {
"messages": [
"The field `title` is required",
"The field `callback_id` is required",
"The field `elements` is required",
"The field `title` cannot be longer than 24 characters",
"The field `submit_button` cannot be longer than 24 characters",
"The field `submit_button` can only be one word",
"The field `callback_id` cannot be longer than 255 characters",
"The field `elements` must be a list",
"The field `elements` has to include at least one element",
"The field `elements` cannot include more than five elements",
"Element 0 must be an object",
"Element 1 is missing required field `type`",
"Element 2 has an invalid `type`",
"Element 3 is missing required field `name`",
"Element 4 is missing required field `label`",
"Element 5 has a repeated name",
"Element 6 field `name` cannot be longer than 300 characters",
"Element 7 field `hint` cannot be longer than 150 characters",
"Element 8 field `label` cannot be longer than 24 characters",
"Element 9 has an invalid `subtype`",
"Element 10 field `min_length` must be between 0 and 150 (inclusive)",
"Element 11 field `max_length` must be between 1 and 150 (inclusive)",
"Element 12 field `value` cannot be longer than 150 characters",
"Element 13 field `placeholder` cannot be longer than 150 characters",
"Element 14 field `min_length` must be between 0 and 500 (inclusive)",
"Element 14 field `max_length` must be between 1 and 500 (inclusive)",
"Element 15 field `value` cannot be longer than 500 characters",
"Element 16 field `placeholder` cannot be longer than 150 characters",
"Element 17 field `placeholder` cannot be longer than 150 characters",
"Element 18 field `options` must be a list",
"Element 19 field `options` must have at least one option",
"Element 20 field `options` must have fewer than 100 options",
"Element 21 `options` item is missing required field `label`",
"Element 22 `options` item is missing required field `value`",
"Element 23 `options` item `label` field cannot exceed 75 characters",
"Element 24 `options` item `value` field cannot exceed 75 characters"
]
}
}

If your form was invalid, Slack will try to provide a detailed accounting of why and provide the validation_errors error. Look for the response_metadata node and the messages array contained within for human-readable validation errors.

When we encounter an error with a specific form element, we'll indicate which element by a zero-indexed integer: 0 indicates the first provided element, 1 the second, and so on.

Errors

This table lists the expected errors that this method could return.
However, other errors can be returned in the case where the service is down
or other unexpected factors affect processing. Callers should always
check the value of the ok params in the response.

Error

Description

validation_errors

The provided dialog could not be validated.

missing_trigger

No trigger_id argument was presented.

missing_dialog

No dialog argument was presented.

trigger_exchanged

The provided trigger_id has already been exchanged.

trigger_expired

The provided trigger_id was presented after the 3 second limit.

invalid_trigger

The provided trigger_id is invalid or cannot be used by this token.

app_missing_action_url

The app associated with the used token doesn't have a Action URL configured in its interactive components settings.

cannot_create_dialog

Something exceptional occurred and the dialog could not be created.

failed_sending_dialog

Something exceptional occurred and the dialog could not be sent.

not_authed

No authentication token provided.

invalid_auth

Invalid authentication token.

account_inactive

Authentication token is for a deleted user or workspace.

no_permission

The workspace token used in this request does not have the permissions necessary to complete the request.

invalid_arg_name

The method was passed an argument whose name falls outside the bounds of accepted or expected values. This includes very long names and names with non-alphanumeric characters other than _. If you get this error, it is typically an indication that you have made a very malformed API call.

invalid_array_arg

The method was passed a PHP-style array argument (e.g. with a name like foo[7]). These are never valid with the Slack API.

invalid_charset

The method was called via a POST request, but the charset specified in the Content-Type header was invalid. Valid charset names are: utf-8iso-8859-1.

invalid_form_data

The method was called via a POST request with Content-Typeapplication/x-www-form-urlencoded or multipart/form-data, but the form data was either missing or syntactically invalid.

invalid_post_type

The method was called via a POST request, but the specified Content-Type was invalid. Valid types are: application/x-www-form-urlencodedmultipart/form-datatext/plain.

missing_post_type

The method was called via a POST request and included a data payload, but the request did not include a Content-Type header.

team_added_to_org

The workspace associated with your request is currently undergoing migration to an Enterprise Organization. Web API and other platform operations will be intermittently unavailable until the transition is complete.

request_timeout

The method was called via a POST request, but the POST data was either missing or truncated.

Warnings

This table lists the expected warnings that this method will return.
However, other warnings can be returned in the case where the service
is experiencing unexpected trouble.

Warning

Description

missing_charset

The method was called via a POST request, and recommended practice for the specified Content-Type is to include a charset parameter. However, no charset was present. Specifically, non-form-data content types (e.g. text/plain) are the ones for which charset is recommended.

superfluous_charset

The method was called via a POST request, and the specified Content-Type is not defined to understand the charset parameter. However, charset was in fact present. Specifically, form-data content types (e.g. multipart/form-data) are the ones for which charset is superfluous.